Greece’s Orthodox Church leader, Archbishop Christodoulos died Monday at his home after months of battle with cancer, church officials revealed. He was 69.

He had been the head of roughly 15 million Greek Orthodox Christians worldwide, including about 10 million in Greece for 10 years.

Archbishop Christodoulos of Athens and all of Greece was the youngest archbishop to lead the church when he was elected in 1998. Seen as the country’s most popular public figure in opinion polls, he was one of the key leaders behind improving ties between Greek Orthodox Church and the Vatican in Rome.

In 2001 he received the late Pope John Paul II in Athens, the first papal visit to Greece in nearly 1,300 years. During his visit, the Pope asked for forgiveness for sins committed against Orthodox Christians during the 1,000 year split between the two traditions.

The Archbishop made himself an historic visit to the Vatican in 2006, when he and the Pope Benedict XVI signed a joint declaration calling for inter-religious dialogue and stating opposition to abortion and euthanasia.

The Archbishop was diagnosed with cancer of the liver and large intestine in 2007, the Associated Press reports. He was then treated in the United States for 10 weeks, but a liver transplant surgery last October was aborted as the cancer had spread. The last few weeks of his life, he was being treated at home after refusing hospital treatment. According to church officials, the Archbishop died around 5 a.m. in his home in the Athens.

“The way he dealt with his disease and imminent death moved us, sending a unique message of courage and dignity, Greek President Karolos Papoulias said in a statement, Reuters reports.

“He was an enlightened church leader whose work brought the church closer to society, closer to modern problems and to young people,” Prime Minister Costas Karamanlis said in a statement.

The Holy Synod, the church’s top decision-making body, will hold a meeting later on Monday. It has 20 days in which to elect the archbishop’s successor.

A four-day period of mourning has been declared in Greece, while the Archbishop’s body will lie in state in the Athens Cathedral until his funeral scheduled for Thursday, Greek television has reported.